Outlook | Web | Outlook.com | Email
Sending, receiving, and organizing email in Outlook.com
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You could also try opening a private or incognito window and logging in from there.
Outlook login error: contextID cookie mismatch
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(188.79999999999998, 55.00000000000001%, 28%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EK%3C/text%3E%3C/svg%3E)
KateRe
40
Reputation points
Why am I getting this error when I try to log into Outlook: "server_error: The contextID supplied in the request did not have a matching cookie"
Outlook | Web | Outlook.com | Email
Answer accepted by question author
Answer accepted by question author
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(89.60000000000001, 72%, 18%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESI%3C/text%3E%3C/svg%3E)
SD - IA
179.8K
Reputation points
Independent Advisor
Hi,
Try this, please.
"On the webpage, click the Lock icon on the browser's address bar on the left.
Click Cookies.
On the popup that opens, remove all cookies one by one, by selecting each cookie and remove the same.
Reload the page and sign in again using the credentials.
I’m eager to hear back and work together to find a solution.
-
KateRe 40 Reputation points
2026-06-23T07:38:52.7233333+00:00 Thanks for the reply, deleted the cookies and that sorted it. No more errors
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2 additional answers
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AI answer
2026-06-08T14:03:39.6266667+00:00 The error "server_error: The contextID supplied in the request did not have a matching cookie" indicates a mismatch between an identifier stored in the browser cookies and the value expected by the Outlook/OWA service during sign-in. This is similar in nature to issues where a GUID or context value stored in cookies does not match what is stored on the server, so the server blocks the request.
This type of problem is typically caused by:
- Stale or corrupted cookies or cached authentication data in the browser.
- Browser settings or extensions interfering with cookies (including third‑party cookies) or session handling.
To troubleshoot, use steps that address cookie and browser issues:
- Clear cookies and cache for Outlook/OWA
- In the browser, clear cookies and cached data, especially for Outlook/OWA/Outlook.com domains.
- Close all browser windows and sign in again.
- Test in InPrivate/Incognito mode
- Open an InPrivate/Incognito window and try signing in to Outlook/Outlook.com.
- If it works there, the issue is likely related to existing cookies, cache, or extensions in the normal profile.
- Disable browser extensions and reset browser settings
- Temporarily disable all extensions (ad blockers, privacy tools, VPN-related add‑ons, etc.).
- Try signing in again.
- If the problem persists, reset the browser settings to default and retry.
- Check cookie settings (especially third‑party cookies)
- Ensure the browser is not blocking cookies required for Outlook sign‑in.
- If there is a setting to block third‑party cookies, either relax it or explicitly allow Microsoft/Outlook-related URLs.
- Try another browser or device
- Sign in from another browser or device to confirm whether the issue is specific to one browser profile.
If the problem continues after these steps, contact the service or tenant administrator to check for any server-side issues affecting Outlook/OWA sign-in.
References:
AI-generated content may be incorrect. Read our transparency notes for more information. -
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YUKI Cuzz 0 Reputation points2026-07-28T11:17:04.5466667+00:00 To fix the Outlook contextID cookie mismatch error, clear your browser cookies and cache for the site. ### How to Resolve the Error
Clear Site Cookies: Click the lock icon on the browser address bar, go to Cookies, remove all stored cookies for Outlook/Microsoft, and reload the page.
Use Incognito / Private Mode: Try logging in via an InPrivate or Incognito window to bypass stale cookies or extensions.
Disable Extensions: Temporarily turn off ad blockers or privacy extensions that might block session cookies required for authentication.